Impacts of fluoride contamination on food crops grown in rural areas of the African Rift Valley

Abstract

The consumption of fluoride-rich food products can represent a major source of fluoride (F) exposure for humans, contributing, together with the consumption of F-rich drinking-water, to enhance the hazard of incurring severe diseases known under the name of endemic fluorosis. Even though the connection between the environmental F contamination and the fluorosis disease is well recognised, the analyses of literature brought to the light the gap of knowledge on the uptake behaviour and the effects of F on food crops, particularly regarding some of the strongest affected areas, such as the East African Rift Valley. Field experiments conducted in rural areas of North Tanzania confirmed, as previous observed in the literature, the tendency of plants to accumulate F mostly in the root system to the disadvantage of those crops whose edible part is the underground organs. However, a substantial accumulation of F in other plants edible parts (e.g. leaves, fruits or seeds) was also observed, underlining that the consumption of the considered food items can substantially contribute to F-correlated diseases, especially in earlier ages. Moreover, the protracted use of high-F contaminated waters along the crop cycle, as tested in a greenhouse pot experiment, was observed to considerably affect the quality of the soil leading to a significant rise of its water-soluble F concentration and the increase of F accumulation in plants organs such leaves and stems in a dose-dependent manner